Caped stent

ABSTRACT

An intravascular stent having a stent body and at least one cover overlying the stent body to cover the first portion of the stent body. The cover has a first region attached to the stent body and a second region unattached to the stent body. Multiple covers can be attached to the stent body in overlapping arrangement, each cover having a free unattached end. The free ends reduce the overall stiffness of the stent.

CROSS-REFERENCE(S)

This application is a continuation in part of application Ser. No.16/214,130, filed Dec. 9, 2018, the entire the contents of which isincorporated by reference herein.

FIELD OF THE INVENTION

The present disclosure relates to endovascular devices used to treataneurysms and fistulas within unhealthy blood vessels, and moreparticularly, to covered stents positionable within blood vessels.

BACKGROUND OF THE INVENTION

The prior art teaches the use of a number of devices to treat aneurysms.A common blood vessel difficulty is the persistent blood flow in theaneurysm sac extrinsic to the endograft. In fact, this is the mostcommon complication after endovascular aneurysm repair (EVAR). Suchendoleaks are ameliorated by a number of means. For example, Walzmanapplication Ser. Nos. 15/732,147 and 15/732,365 (Publication No.2018-0153554) teach the use of hydrogel to prevent endoleaks.

The prior art also teaches endovascular coiling as a minimally invasivetechnique performed to prevent blood from flowing into some saccularaneurysms. This treatment results in the coil inducing embolization(clotting) of the aneurysm, which prevents blood from flowing into theaneurysm, which in turn, prevents rupture and for intracranial aneurysmssubsequent subarachnoid hemorrhage. Endovascular coiling, however, mayresult in procedural complications including thromboembolism, cerebralembolization, aneurysm perforation, parent artery occlusion, coilmigration, arterial dissection, and others. The prior art also teachesstent-assisted coiling. The stent-assisted coiling also has some of thesame shortcomings related to stent placement and placing a stent in theparent artery and requires prolonged use of anti-platelet agents toreduce the risk of thrombosis-based stenosis within the stent.

Some aneurysms and fistulas are ideally treated with covered stents,which can most directly cover the hole of the fistula or the neck of theaneurysm and reconstruct the vessel wall, immediately redirecting bloodflow into the normal path of the parent vessel. However, there arecurrently no covered stents that are effective in the neurovascular orin severely tortuous anatomy in other parts of the body, including forexample splenic artery aneurysms and pulmonary arteriovenous fistulas.

A potentially significant use of covered neuro-stents is for thetreatment of fistulas, particularly for carotid cavernous fistula (CCF)which is an abnormal communication between the cavernous sinus and thecarotid arterial system.

Other treatment of aneurysms includes surgical clipping of anintracranial aneurysm, which involves the application of a clip acrossthe neck of the aneurysm. This treatment has several shortcomingsincluding that it requires an open operation and physical manipulationof the brain. Sometimes surgical bypass is considered as well, buttypically is associated with even higher rates of morbidity andmortality.

Additionally, the prior art teaches the use of flow diversion devices todivert flow away from the aneurysm by placing a mesh stent or astructure similar to a stent, on the aneurysm neck along the parentartery. The use of these devices allows for thrombus formation insidethe aneurysm. However, increased technical complications can developfollowing the deployment of flow diverters. Additionally, because theydo not completely block flow, they are not effective in the treatment ofmost fistulas and ruptured vessels. Similarly, there is currently noeffective vessel-sparing treatment of an iatrogenic rupture of anintracranial artery. Current treatment requires closing the rupturedartery with coils and/or liquid embolics to stop the bleeding, usuallywith significant resulting morbidity from ischemic injury to thatarterial territory. Furthermore, when treating aneurysms with thesedevices, the aneurysm thromboses over time, so there is a lag period,and is not immediately cured. This leaves the patient at risk ofaneurysmal rupture during the lag period. This can be especiallyproblematic when treating ruptured aneurysms, which have high short-termre-rupture rates.

A need exists for an endovascular device capable of endovascularintervention for immediate cure of select intravascular aneurysms orfistulas, while ameliorating the difficulties and shortcomingsassociated with the currently available technologies. More particularly,a need exists for a covered stent which allows the stent freedom ofmotion and bending without kinking around tight bends in tortuousanatomy.

Most covered stents involve producing a cylinder of a stent “skeleton”or “frame” out of semi-rigid materials such as metal alloys, and thenattaching an impermeable “cover” to the frame. The prior art teachessuch attachments are diffuse and located throughout the covering of thestent, along fixed intervals of the covering and frame, and consequentlysignificantly limit flexibility of the device. The need exists for astent capable of safe and effective delivery and deployment intotortuous vessels to effectively divert blood flow away from an aneurysm,fistula, or ruptured vessel while allowing blood to flow to healthytissue distal to the targeted treatment area and still resulting inblood stasis and thrombus formation inside the aneurysm or fistula.Thus, a need exists for a covered neuro stent as well as a covered stentwhich is capable of use in other tortuous anatomy outside of the brain.

SUMMARY OF THE INVENTION

The present invention overcomes the problems and deficiencies of theprior art. The present invention provides a covered stent device capableof safe and effective delivery and deployment into tortuous vessels toeffectively divert blood flow away from an aneurysm, fistula, orruptured vessel while allowing blood to flow to healthy tissue distal tothe targeted treatment area and still resulting in blood stasis andthrombus formation inside the aneurysm or fistula, and/or repair andsubsequent healing of the damaged vessel. The covered stents of thepresent invention can be utilized as a neuro stent as well as a used inother tortuous anatomy outside of the brain. These devices can be usedin anatomy that is not tortuous as well.

The present invention achieves the foregoing by providing a stent with afree-floating cover. The free-floating cover is designed to optimizeinsertion in tortuous anatomy as the stent bends and curves duringinsertion through the vasculature. In some embodiments, this is achievedvia a single circumferential attachment point of the cover at one end(which can be as small as about 0.1 mm for example). In someembodiments, a plurality of covers are provided and can be arranged inoverlapping arrangements such as in shingle-like fashion described indetail below. The cover configuration and attachment minimizes stiffnessof the device and allows for bending of the stent without kinking whichcould otherwise occur. Thus, as noted above, its sufficient flexibilityenables its use as a covered stent for neuro applications as well as inother tortuous anatomy outside of brain.

As can be appreciated from the discussion of the various embodimentsbelow, the stent can have a single cover or can have multiple covers atvarious locations and arrangements.

In some embodiments, the covers are arranged as overlapping geometricshingles attached to the stent (frame) on only one side, comprising lessthan 70% of the length of said shingles, with the shingle optionallyattached only along a limited segment of the circumference and/orlongitudinal surface of the frame. Additional overlapping shingles andtheir independent attachments can extend over a covered segment anduncovered segment of the stent, resulting in complete coverage of saidsegment(s) of the stent. Partial coverage of the stent frame with theoverlapping, e.g., shingled covers, can be provided in otherembodiments, with the covers together covering a majority, oralternatively, a minority, of the length of the frame. Some embodimentsmay also have more than one covered region.

The covered stents of the present invention can optionally be deployedunder flow arrest, via pharmacologic means, or via delivery through aballoon guide catheter with temporary balloon inflation or other means,to minimize the possibility of blood flow folding or bunching the cover,e.g., fabric, as it is unsheathed. Furthermore, if a portion of thestent cover is not well apposed to a vessel wall, as can occur when itis overlapping a large fistula, a second similar covered stent can beplaced inside the first covered stent, and the frame of the firstcovered stent will help secure the cover(s) of the second covered stent.Similarly, a different covered stent can be used as the initial outerstent, provided such outer stent has small enough interstices that thecover(s) of the second inner stent cannot herniate through thoseinterstices.

The stent covers of the present invention can fully encircle, or, inalternate embodiments, partially encircle, a given segment of the stent(frame) such that the stent is covered only along a portion of itscircumference while being uncovered at a different circumferentialside/portion of the same segment. This can sometimes allow preservationof the origin of a branch vessel that might arise from the parent vesselalong the same segment of said parent vessel, for example, opposite to afistula or the neck of an aneurysm.

In accordance with one aspect of the present invention, an intravascularstent is provided comprising a) a stent body having a longitudinal axis,a first portion, a second portion and a plurality of openings; b) afirst cover overlying the stent body to cover the first portion of thestent body and extending longitudinally over the first portion, thefirst cover having a first region and an unattached region, theunattached region having a free end, the first cover attached to thestent body at the first region; and c) a second cover overlying thestent body to cover the second portion of the stent body and extendinglongitudinally over the second portion, the second cover having a firstregion, a second region and an unattached region having a free end. Thefirst cover overlaps the first region of the second cover and a portionof the unattached region of the second cover is not overlapped by thefirst cover.

In some embodiments, the first cover overlaps the second cover such thata majority of the second cover is not overlapped by the first cover. Inother embodiments, the first cover overlaps the second cover such that amajority of the second cover is overlapped by the first cover.

In some embodiments, the first cover and/or the second cover areattached to an inner wall of the stent body; in other embodiments, thefirst cover and/or the second cover are attached to an outer wall of thestent body.

The stent body (skeleton/frame) may have a single layer or two or morelayers welded together at one or more points. The stent body may bewoven, or braided, or laser cut, or combinations of these—either varyingalong its length or two or more different frame types welded together atone or more points. The skeleton/frame can me made of one or moremetals, metal alloys, or other suitable non-metallic materials.

In some embodiments, the stent is inserted into a body of a patient withthe first and second stent covers attached to the stent body. That is,the covers are attached in the manufacturing process.

In some embodiments, the first and second covers are attached to anouter wall of the stent body and a second stent body is positioned overthe first and second covers. This can sometimes be accomplished in vivoby first deploying the second stent body, and subsequently deploying thefirst stent with the attached stent covers within the confines of thesecond stent, thereby allowing the free-ends of the covers e.g., theshingled free ends, to be pinned between the two stent skeletons,minimizing the chance of an endoleak between overlapping covers. Inother embodiments, the two stent bodies are inserted together.

In some embodiments, multiple stents each have multiple covers e.g.,shingles, and are placed in vivo inside each other in a telescopingfashion to further minimize the risk of leaks through or around thecovers. In some embodiments there may also be an additional substance,including but not limited to hydrogel, that coats some or all of theskeleton frame and/or the covers, which can swell in vivo and furtherminimize the chance of leaks between covers, e.g., shingles, and/orbetween the stent or stents and the vessel wall.

In some embodiments, the first and second covers extend around a full360 degrees of the stent body; in other embodiments, the first andsecond covers extend around less than a full 360 degrees of the stentbody. In some embodiments, the first and second covers together coverless than an entire length of the stent body.

In some embodiments the covers are cylindrically shaped; in otherembodiments they are semi-cylindrical shaped; in other embodiments theyare substantially triangular shaped. Other configurations and geometricshapes are also contemplated, such as like scales on a fish.

In some embodiments, the first cover and second cover are each attachedto the stent body at an attachment site, and the first and second coversare expandable independent of the frame except at the attachment site.

In some embodiments, a third cover is provided overlying the stent bodyto cover a third portion of the stent body and extending longitudinallyover the third portion, the second cover overlapping a portion of thethird cover so the first, second and third covers form a shingle-likearrangement. Additional covers are also contemplated.

In accordance with another aspect of the present invention, anintravascular stent is provided comprising a) a stent body having alongitudinal axis and a plurality of openings; and b) a first coveroverlying the stent body to cover a first segment of the stent body andextending longitudinally over the first segment of the stent body, thefirst segment having a first region and a second region. Upon bending ofthe stent body, a portion of the first cover moves axially with respectto the stent body so a length of the stent body covered by the firstcover may be reduced along the outer curve, as the stent body typicallyelongates along the outer curve and the cover length remains constant. Alength of the stent covers relative to the stent body may increase alongthe inner curve, as the stent body typically shortens along an innercurve.

In some embodiments, a second cover overlying the stent body is providedto cover a second segment of the stent body, said second segment havinga first region and a second region and upon bending of the stent body, aportion of the second cover moves axially with respect to the stentbody.

In some embodiments, one end of the stent has no covering. In someembodiments, both the proximal and distal end of the stent have nocoverings. Similarly, branched stents are contemplated as well, withboth covered and uncovered ends in various embodiments. In someembodiments, various configurations of multiple similar and/ordissimilar stents may also be used. In some embodiments, the stent maybe covered at one or more ends and have one or more uncovered segmentselsewhere along a length as well.

In some embodiments, upon bending of the stent body, a portion of thecover moves with respect to the stent body. In some embodiments, uponbending of the stent body, a portion of the stent body moves relative tothe cover. In some embodiments, upon bending of the stent body, aportion of the stent body moves relative to the one or more covers. Insome embodiments, the first cover overlaps an attachment region of thesecond cover without overlapping the free end of the second cover.

In some embodiments, the first cover and second cover are each attachedto the frame, each at an attachment site, which may be separate or thesame for both covers, and the first and second covers are expandableindependent of the frame except at the attachment site. The attachmentsite or sites may be a single point, a line, another shape, acircumference of the frame or part of a circumference of the frame. Inpreferred embodiments, each cover has its own independent attachmentsite. In some embodiments, the first cover overlaps a partial portion ofthe second cover such that a majority of the second cover is notoverlapped by the first cover. In other embodiments, a majority of thesecond cover is overlapped by the first cover.

In some embodiments, the first and second stent covers are attached tothe stent body prior to insertion of the stent and placement of thestent within the vessel.

In some embodiments one or more covers are inside the frame. In someembodiments, one of more covers are on the outside of the frame. In someembodiments, one or more covers are inside the frame and one of morecovers are on the outside of the frame. In some embodiments, one or morecovers are in between layers of the frame. In some embodiments, one ormore covers are inside the frame and one of more covers are on theoutside of the frame and/or one or more covers are in between layers ofthe frame.

In accordance with another aspect of the present invention anintravascular stent is provided comprising a stent body having alongitudinal axis, a first portion, a second portion and a plurality ofopenings. A first cover is arranged to cover an axial segment of thestent body. The first cover has an attachment end attached to the stentbody and an opposing free end which are movable with respect to thestent body to reduce a stiffness of the stent body. That is, the coverallows for more flexibility of the stent and less tendency to kink sincethey are attached only at one end.

In some embodiments, a second cover is provided having an attached endand an opposing free and end movable with respect to the stent body toreduce stiffness.

In some embodiments, each of the first and second covers combined extendover less than an entire length of the stent body. Alternatively, theyextend the entire length. Alternatively, they can extend beyond theentire length.

In accordance with another aspect of the present invention, a method ofpreventing an endoleak in a vessel of a patient is provided comprisingdeploying a first stent across an opening in a vessel and subsequentlyinserting a second stent having a frame and a first cover within thefirst stent such that the first cover extends across the opening in thevessel. The first cover has a first end attached to the frame and asecond free end unattached to the frame. Insertion of the second stentwithin the first stent pins the first cover between the first and secondstents. The opening in the vessel could be for example an opening at afistula or at a neck of an aneurysm.

In some embodiments, the second stent has a second cover having anattached end and a free end, the free end of the first cover overlyingthe attached end of the second cover, and the free end of the firstcover pinned against the second cover to limit flow of blood between thefirst and second covers.

In some embodiments, the first stent is composed of a woven materialand/or the second stent is composed of a non-woven material, which insome embodiments can be metallic or a polymeric material. The firstand/or second stent can be balloon expandable or self-expanding. In someembodiments, the first and second stents have different porosities. Insome embodiments, the second stent has a porosity of greater than 80%.

In some embodiments, at least a part of the stent body/frame and/or thecover (or multiple covers) has adhered hydrogel to help preventendoleaks.

In accordance with another aspect of the present invention, a method ofdelivering a stent within a vessel of a patient is provided comprising:

a) inserting a delivery member into the vessel, the delivery membercontaining a stent having a frame and a first cover overlying a firstportion of the frame to cover the first portion of the frame andextending longitudinally over the first portion, the first cover havinga first region and an unattached region, the unattached region having afree end, the first cover attached to the frame at the first region; and

b) exposing a first section of the stent from the delivery member suchthat the first section expands into contact with a wall of the vessel,the first region of the first cover being pinned against the wall of thevessel while the free end of the first cover remains spaced from thevessel wall as a second section of the stent is contained within thedelivery member.

In some embodiments, the stent has a second cover overlying a secondportion of the frame to cover the second portion of the frame andextending longitudinally over the second portion, the second coverhaving an attached region and an unattached region, the unattachedregion of the second cover having a free end, and the first coveroverlying the attached region of the second cover. In some embodiments,during exposing the first portion of the stent, at least a part of thesecond cover is contained within the delivery member.

In accordance with another aspect of the present invention, anintravascular stent is provided positionable within a vessel of apatient comprising a) an outer layer composed of a woven material; andb) an inner layer positioned within the outer layer, the inner layercomposed of an expandable material and movable from a collapsedcondition to an expanded condition to facilitate expansion of the outerlayer within the vessel.

In accordance with another aspect of the present invention, anintravascular stent is provided positionable within a vessel of apatient comprising a) an outer layer composed of a woven material; andb) an inner layer positioned within the outer layer, the inner layercomposed of an expandable material and movable from a collapsedcondition to an expanded condition to facilitate expansion of the outerlayer within the vessel.

The expanding material can be self-expanding or balloon or mechanicallyexpandable.

In some embodiments, the inner layer and outer layer have differentporosities. In some embodiments, the inner layer has a porosity greaterthan the porosity of the outer layer. In some embodiments, the porosityof the inner layer is between about 70% and about 99.9%. In preferredembodiments the porosity could be greater than 80%. In some embodiments,the porosity range of the outer stent could be between 0% to about 80%,and in preferred embodiments about 75% porosity or less.

In accordance with another aspect of the present invention, anintravascular stent is provided having an outer layer of a firstporosity and a second layer of a second porosity different than thefirst porosity.

In some embodiments, the outer layer has a length equal to the length ofthe inner layer. In other embodiments, the outer layer has a length lessthan a length of the inner layer. In other embodiments, the outer layerhas a length greater than a length of the inner layer.

In some embodiments, one or more covers are attached to an outer wall ofthe inner layer and/or are attached to an inner wall of the inner layerand/or are attached to an outer wall of the outer layer and/or areattached to an inner wall of the outer layer. In some embodiments, thecovers have and attached region and an unattached region having a freeend. The covers can be arranged in a non-overlapping or an overlappinge.g., shingle-like, arrangement.

In some embodiments, the inner layer is inserted into the outer layerafter the outer layer is positioned within the patient's body. In otherembodiments, the inner layer is attached to the outer layer and insertedtogether into a patient's body.

In some embodiments, multiple stents, each having multiple covers, e.g.,shingled covers, are placed in vivo inside each other in a telescopingfashion to further minimize the risk of leaks through or around thecovers. In some embodiments, there may also be an additional substance,including but not limited to hydrogel, which coats some or all of theframe and/or the covers, which can swell in vivo and further minimizethe chance of leaks between shingles and/or between the stent or stentsand the vessel wall.

In preferred embodiments, the stent is self-expanding. In otherembodiments it can be balloon-mounted and balloon expandable. In someembodiments it is partly and/or fully re-sheathable. It may optionallybe attached to a pusher wire. It may also be detachable via mechanical,hydrostatic, electrical, thermal, or other modalities.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those setforth above will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein:

FIG. 1 is a perspective view of a cover of the caped (covered) stent inaccordance with one embodiment of the present invention;

FIG. 2 is a perspective view of a stent (frame) of the caped (covered)stent in accordance with one embodiment of the present invention;

FIG. 3 is a perspective view showing the cover of FIG. 1 positionedwithin the stent body of FIG. 2;

FIG. 3A is a perspective view of an alternate embodiment of the capedstent of the present invention wherein the cover is inside the stent(frame) and extends beyond a length of the stent, the caped stent showninside a vessel;

FIG. 3B is a perspective view of the caped stent of FIG. 3A;

FIG. 3C is a view similar to FIG. 3B showing the free movement of theframe relative to the free portion of the cover when the caped stent isbent during insertion or use;

FIG. 3D is a view similar to FIG. 3A showing an alternate embodiment ofthe caped stent of the present invention wherein the cover is outside(external) the stent body, the caped stent shown inside a vessel;

FIG. 3E is a perspective view of the caped stent of FIG. 3D shownoutside the vessel;

FIG. 3F is a view similar to FIG. 3E showing the free movement of thecover when the caped stent is bent during insertion or use;

FIG. 3G is a perspective view of an alternate embodiment of the capedstent of the present invention having two external axially spacedcovers;

FIG. 4 is a perspective view similar to FIG. 2 except showing a meshstent instead of stent formed of wire struts;

FIG. 5 is a perspective view showing the mesh stent of FIG. 4 having aninternal cover attached at a distal end of the cover;

FIG. 5A is a perspective view similar to FIG. 5 except having a coverpositioned over the mesh stent, the cover attached at a distal end ofsaid cover;

FIG. 5B is a view similar to FIG. 5A except the external cover isattached to the mesh stent at a proximal end of the cover;

FIG. 6 is a perspective view of an alternate embodiment of the covers ofa caped stent of the present invention, the covers shown in overlappingarrangement;

FIG. 6A is a perspective view of a caped stent of the present inventionshowing the covers of FIG. 6 positioned over the stent body;

FIG. 7 is a perspective view of an alternate embodiment of the covers ofa caped stent of the present invention, the three covers shown inoverlapping arrangement;

FIG. 7A is a perspective view showing the covers of FIG. 7 over thestent body;

FIG. 7B is a longitudinal cross-sectional view of the caped stent ofFIG. 7A;

FIG. 7C is a perspective view of an alternate embodiment of the capedstent of the present invention having three covers in overlappingarrangement over the stent body, the proximal and distal coversoverlapping the middle cover;

FIG. 7D is a longitudinal cross-sectional view of the caped stent ofFIG. 7C;

FIG. 7E is a perspective view of an alternate embodiment of the capedstent of the present invention having three covers in overlappingarrangement partially covering the stent body, i.e., extending less than360 degrees about the stent body;

FIG. 7F is a perspective view of an alternate embodiment of the capedstent of the present invention having multiple covers in overlappingarrangement over the stent body, the covers being triangular shaped;

FIG. 7G is a perspective view of an alternate embodiment of the capedstent of the present invention having multiple covers in overlappingarrangement over the stent body, the covers being triangular shaped andcovering less than a majority of the length of the stent body andextending less than 360 about the circumference of the stent body;

FIG. 8 is a perspective view of the caped stent of the present inventionshowing the three covers of FIG. 7 over the stent body with ends of thestent body uncovered;

FIG. 9 is a perspective view of an alternate embodiment of the capedstent of the present invention having a series of covers arranged incircumferential overlapping arrangement, the covered stent shown in thecollapsed delivery configuration (condition);

FIG. 10 is a cross-sectional view through a covered segment of the capedstent of FIG. 9 showing the covered stent in the collapsed deliveryposition;

FIG. 10A is perspective view of the caped stent of FIG. 9 showing thecovered stent in the expanded placement (deployed) configuration(condition);

FIG. 10B is a cross-sectional view through a covered segment of thecaped stent of FIG. 10A in the deployed configuration;

FIG. 10C is a cross-sectional view through a covered segment of analternate embodiment of the caped stent of the present invention shownin the collapsed configuration;

FIG. 10D is a cross-sectional view through of the caped stent of FIG.10C shown in the deployed configuration;

FIG. 11A is a perspective view of an alternate embodiment of the capedstent of the present invention having a series of covers incircumferential overlapping arrangement;

FIG. 11B is a perspective view of an alternate embodiment of the capedstent of the present invention having a series of covers incircumferential overlapping arrangement;

FIG. 11C is a perspective view of an alternate embodiment of the capedstent of the present invention having a series of covers incircumferential overlapping arrangement, the covers extending over lessthan the 360 degrees about the stent body;

FIG. 11D is a perspective view of an alternate embodiment of the capedstent of the present invention having a series of circumferentialoverlapping covers overlapping a cover extending around the entirecircumference of the stent body;

FIG. 12 is a view similar to FIG. 10A showing an alternate embodimentwith additional covers, the covered stent shown in the deployed position(condition);

FIG. 13 is a side view of a self-expanding stent body of a covered stentof the present invention in the process of deployment from a deliverydevice;

FIG. 14 is a perspective view of an alternate embodiment of the capedstent of the present invention having an outer stent overlying thecovers covering the stent body;

FIG. 15 is a perspective view of the caped stent of FIG. 14 withportions of the outer stent removed for clarity; and

FIG. 16 is a longitudinal cross-sectional view of the caped stent ofFIG. 14.

FIG. 17 is a perspective view of an alternate embodiment of the capedstent of the present invention having two stent layers, with a portionbroken away to show the cover.

FIG. 18 is a perspective view of another alternate embodiment of thecaped stent of the present invention having two stent layers, with aportion broken away to show the cover.

FIG. 19A is a perspective view showing a caped stent in accordance withan embodiment of the present invention positioned adjacent a vesselopening, the arrow depicting leakage under the middle cover.

FIG. 19B is a view similar to FIG. 19A showing the caped stentpositioned within an outer stent.

FIG. 20A is a perspective view of an alternate embodiment of the of thepresent invention having two stent layers, with a portion broken away toshow the inner stent layer.

FIGS. 20B and 20C are cross-sectional and perspective views of analternate embodiment of the present invention having two stent layers.

FIGS. 20D and 20E are cross-sectional and perspective views of anotheralternate embodiment of the present invention having two stent layers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a covered (caped) stent configured fordelivery through vessels, such as tortuous vessels, for deployment invessels to effectively divert blood flow away from an aneurysm, fistula,or ruptured vessel while allowing blood to flow to healthy tissue distalto the targeted treatment area and still resulting in blood stasis andthrombus formation inside the aneurysm, fistula, or other coveredlesion, or otherwise sealing closed an unwanted hole or outpouching. Thecovered stents of the present invention can be utilized in theneuro-vasculature as well as in other tortuous anatomy outside of thebrain, in luminal structures and in other anatomies.

The covered (caped) stents of the present invention reduce or preventkinking of the stent body (frame) as it bends due to the curves in thevasculature. This increased flexibility of the covered stents of thepresent invention is achieved by the attachment and configuration of thecovers which provides a free-floating cover over the stent body. Thatis, the attachment of the cover to the stent body is minimized, therebyleaving a region that is unattached and free-floating. In this manner,when the covered stent is bent, the cover does not restrict thebendability of the stent body, but accommodates for such bending.

The covered stents of the present invention can move at sharper anglesthan covered stents of the prior art. The covered stents of the presentinvention present no sharp edges, and are prone to less kinking, therebyreducing risks of abrasion, puncture, rupture, narrowing, occlusion, orother damage to the target vessel, while allowing better conformance tothe vessel wall in addition to a continuous seal. It also allows safeand effective delivery and deployment in many vessels that are moretortuous than what current stents permit. In some embodiments, the sealto the vessel wall may be further enhanced via a full or partial coatingof hydrogel or another substance. The cape/cover design/configuration ofthe present invention eliminates, or at least ameliorates, rigidityassociated with covered stents by allowing free movement of the cover(cape) in comparison to covers of the prior art which are attached alonga length, attached at multiple points, or attached at opposing ends.This feature allows the user easier deployment of the covered stent ofthe present invention than existing covered stents of the prior artbecause existing stents have covers limiting bending, thus increasingstiffness. Furthermore, in stents of the prior art with fixed and fullyattached coverings, the fixation of the covering (covering attachments)to the frame does not allow appropriate lengthening of the stent alongthe outside of a curve and corresponding shortening of the stent alongthe inner curve which makes stents of the prior art stiffer and moredifficult to deliver and deploy in tortuous anatomy. In other words, thefixed and fully attached coverings of prior stents restrict the bendingof the stent while in the covered stents of the present invention, thefree ends, and thus free movements of the stent frame relative to thecovers, enable more or full flexibility of the stent.

The present invention contemplates the use of one or more covers overthe stent body. When a plurality of covers are provided, they can bearranged in an overlapping configuration as described in detail below.The overlapping configuration is also advantageous for controlleddelivery of the stent as described below since the stent can maintainits flexibility when only one of the covered portions is deployed in thevessel. The covers can be of various configurations and can cover variedamounts of the stent body, also discussed in detail below. Some stentsmay have fenestrations in the covers and/or the frame as well.

Referring now to the drawings and particular embodiments of the presentdisclosure, wherein like reference numerals identify similar structuralfeatures of the devices disclosed herein throughout the several views,there are illustrated several embodiments of the covered stents of thepresent invention.

Referring initially to FIGS. 1-3, a first embodiment of the caped(covered) stent of the present invention is illustrated. The cover orseal element 130 is shown in FIG. 1 and the stent body 230 is shown inFIG. 2. Preferably, such covers have limited or no porosity to bloodand/or plasma. Note the cover 130, as well as the other covers disclosedherein, are also referred to herein as a “cape” or “sealing element” or“cape element.” Also note the stent body 230, as well as the other stentbodies disclosed herein, are also referred to herein as the “stent” or“frame” or “stent frame” or ‘skeleton” or “scaffold.” The cover(s) areattached to the stent body, either internally such that they areattached to an inner wall of the stent body, or externally such thatthey are attached to an outer wall of the stent body, and/or in theinterstices. Together, the device having the one or more covers attachedto the stent body is referred to herein as the “caped stent” or “coveredstent.”

With continued reference to FIGS. 1-3, the cover (cape element) 130 hasa connection or attachment element 100 at one end for attachment toelement 290 on stent body 230. Various types of connections/attachmentare contemplated such as welds, metallic string, fabric string andothers. Opposite the end containing the connection element 100 is freeend 160 which is not attached to the stent body 230. The cover 130 ispreferably impermeable to provide a seal. It may also be permeable,partially permeable, or completely impermeable to various fluids andcomponents.

Cover 130 can be of various lengths (from its attached end to its freeend 160) according to the size of the target vessel, according to thedesired area of the stent to be covered/sealed, and/or and according tothe desired amount of flexibility in a region of the stent and/oraccording to the number of covers. The cover 130 in some embodiments isapproximately 30% longer than the area of the target vessel intended tobe covered in order to prevent rigidity at bends while allowinglengthening of the stent on the outer curve and still maintaining thedesired coverage. More particularly, insofar as the cover 130 is onlyattached to stent 230 outside the seal-deployment area, the stent 230will be more flexible than a stent having a cover attached or atmultiple sites along its length. In alternate embodiments, the cover ismore than 30% longer than the area of the target vessel to be covered.In other embodiments, the cover is less than 30% longer. Such variouslengths of the cover, and various lengths of the extent of the stentbody covered, are applicable to each of the covered stent embodimentsdisclosed herein.

FIG. 2 depicts the stent body 230 which is translucent, permeable andhas a first end 200, a second end 260, and stent attachment element 290closer to first end 200. The stent body 230 (as well as the other stentbodies (stent frame/skeleton) disclosed herein) can be formed from aplurality of metal struts as shown. The stent 230 can alternatively beformed from a plurality of wires or from a cut, e.g., laser cut, tubularmember, a woven mesh, a braid, a polymeric material or combinations ofthese or other materials and methods—either varying along its length ortwo or more different frame types welded together at one or more points.The stent body may have a single layer or two or more layers weldedtogether at one or more points. Examples are described below.

The cover 130 can be shown attached inside (internal) the stent body 230(FIG. 3), i.e., attached to an inner wall of the stent body 230, andpositioned so it is spaced proximally from the first end 200 anddistally of the second end 260 of the stent body 230. This leavesuncovered (exposed) stent regions at the proximal and distal regions.The length of the uncovered regions can vary. The cover canalternatively be positioned outside (external) the stent body, i.e.,attached to an outer wall of the stent body, as in alternate embodimentsdiscussed herein. There may be no uncovered segments in some embodimentsas well.

The stent body 230 can be in the form of metal struts (or wires) whichare collapsed during delivery through a delivery sheath or crimped ontoa balloon to present a reduced profile and expand once delivered fromthe sheath to a larger diameter. The stent can be self-expanding orexpandable by a balloon or other expanding mechanism/structurepositioned within the stent. The expanded state is shown in FIGS. 2 and3, with FIG. 3A showing an example of a covered stent expanded withinvessel V.

Alternatively, the stent body can be composed of a mesh with smallpermeable openings as in the embodiment of FIGS. 4 and 5. In thisembodiment, stent body 230′, like stent body 230 of FIG. 2, has a firstend 200′, a second end 260′ and an attachment element 290′. In all otherrespects, the covered stent of FIGS. 4 and 5 is the same as the coveredstent of FIG. 3. Cover 130 is positioned within the stent body 230′.However, alternatively it could be positioned outside the stent body asin the embodiment of FIGS. 5A and 5B. Covered stent 650 of FIG. 5A has amesh stent 670 with a cover 660 positioned thereover and attached atattachment region 662 at a distal portion of the cover 660. Proximalregion/end 664 of cover 660 and the remainder of the cover is unattachedfor free floating movement. The length of the attachment can vary fromless than one nanometer to 1 meter. The cover 660 has a length less thana length of the stent body 670 leaving distal region 672 and proximalregion 674 of stent body 670 uncovered. Other lengths and proportionsare also contemplated.

Covered stent 680 of FIG. 5B is identical to covered stent 650 of FIG.5A except that cover 681 has an attachment region 682 at a proximalportion/region of the cover 681 so that a distal region is freefloating. Distal region 684 and proximal region 694 of stent body 692are uncovered. As noted above, the length of the cover in this as wellas in the other embodiments disclosed herein can vary from that shownand the cover can be placed closer toward a distal end or closer towarda proximal end rather than in a medial region as in FIGS. 5A and 5B.That is, the covers are shown over a medial portion of the stent bodybut alternatively can be positioned more distal or more proximal and canhave a shorter or longer length than that shown. In any event, thecovers are attached at one end region so that the opposing end region isfree floating and can move relative to the stent body. There can also bea single cover, or multiple covers. In embodiments with multiple coversthey can be fully overlapping, partly overlapping, not overlapping,and/or various combinations.

Note the mesh stent body of FIGS. 4-5B can be provided in any of theother embodiments disclosed herein.

The advantage of the free end of the cover can be understood bycomparing FIGS. 3B and 3C. In FIG. 3B, the covered stent 250 is in astraight/linear position. (FIG. 3A shows the covered stent 250 in alinear position within vessel V). The cover 260 is attached to an innerwall of stent body 252 at attachment region 266. When the covered stent250 is bent, e.g., bent around a curve in a vessel, the free unattachedend 264 can move relative to the stent body, e.g., slide (e.g., axially)within the stent, as shown in FIG. 3C. Thus, proximal region 264 ofcover 260 slides within the stent body 252 so a shorter length L2compared to length L1 is exposed as the stent lengthens along the outercurve. Along the inner curve, the stent frame body may shorten so theextent of coverage by the cover lengthens relative to the length of thestent frame/body along the inner curve. This enhances the flexibility ofthe stent since the bending is not restricted by the cover due to therelative movement of regions of the cover and the underlying (oroverlying) stent body. That is, such movement maintains the flexibilityof the stent since if the cover 260 was attached at both ends ratherthan having an unattached end for free movement, it would restrictbending of the stent body 252. This change is depicted in FIG. 3C—thecover relative “shortening” along the “outer” curve relative to thesplaying and possibly lengthening stent frame, but relative“lengthening” of the cover relative to the stent frame along the “inner”(inferior) curve where the stent frame may shorten.

Note the free end can also be slightly longer to enable play uponbending of the stent body or otherwise allow movement. Note in thisembodiment, the cover 260 extends beyond the proximal edge 256 of thestent body 252 so there is a region 264 not within the stent frame. At adistal end, the cover 260 is spaced proximally from the distal edge 254.Alternatively, the cover can extend distal of the distal edge 254 inlieu of or in addition to it extending beyond the proximal edge 256.Also, alternatively, the cover 260 can terminate within the stent body252 so that it terminates at a proximal end distal of the proximal edge256 of the stent body 252. In either case, the free end of the cover canmove relative to the stent body and independently thereof.

Note the caped stent is shown in FIG. 3C in the expanded condition, itbeing understood however that the bend could occur during delivery atwhich state the stent would be collapsed/compressed to a conditionhaving a smaller diameter within the delivery member to provide a lowerprofile for insertion. Once at the target site, it is released from thedelivery member and can return to its expanded, e.g., larger diameter,condition. The free floating movement of the unattached region of thestent can occur in the delivery and/or placement positions of thecovered stent.

As noted above, the cover can alternatively be placed outside the stentbody to attach to the outer wall of the stent body. This is shown forexample in the embodiment of FIGS. 3D-3F. Covered stent 270, shownwithin the vessel V in FIG. 3D, has a stent body 272 and a cover 280attached at attachment region 286. Distal end 284 of cover 280terminates proximally of distal edge 273 of stent body 272, leavingdistal region 276 of stent body 272 uncovered. Alternatively, or inaddition, a proximal region of stent body 272 could be uncovered. Thelength of the uncovered regions can vary so that the exposed regions areof greater length or of a smaller length. Also, the cover 260 is shownattached at its distal end but alternatively could be attached at aregion spaced from the end or at a proximal end. Such alternateattachment locations are applicable to other covered stents disclosedherein. FIG. 3F illustrates the covered stent 270 when bent toillustrate movement of the stent body relative to the free end of thecover 280. When bent, free unattached end 285, on an end opposite theend of the attachment region 286, moves relative to the stent body 272as can be seen by the exposed region 275 of the stent body (as comparedto FIG. 3E), as the stent body flexes and may elongate and/or shortenalong certain sections. As shown, lengthening of the stent along theouter curve decreases the length of coverage of the cover 280 relativeto the stent body, along the outer curve; the shortening of the stentbody along the inner curve may increase the proportion of the length ofthe frame covered along the inner curve, as shown. The relativepositions of the stent body and cover at distal region 276 remainsunchanged due to the cover attachment region 286 adjacent the distalregion 276.

In the alternate embodiment of FIG. 3G, two stent covers 620 and 630 ofcovered stent 600 are attached to stent body 610. The stent covers 620and 630 are axially spaced to leave a medial region 616 of stent bodyregion 610 uncovered. Cover 620 is attached at a distal attachmentregion 622 so that the opposing end 624 is unattached and free floating.Cover 630 is attached at distal attachment region 632 so that opposingend 634 is unattached and free floating. The covers 620 and 630 can beof the same or varying lengths, can be of different lengths than thatshown and can be spaced differently than that shown to leave regions ofalternate lengths of the stent body 610 covered and uncovered. It isalso contemplated that more than two covers can be placed inside oroutside the stent body at radially spaced intervals.

FIGS. 6-16 illustrate alternate embodiments of the covered stents of thepresent invention wherein multiple stent covers are provided, arrangedin partially overlapping fashion. In the embodiments of FIGS. 6-8, thestent covers are arranged axially along a longitudinal axis of the stentbody so that a first stent cover is distal of a second stent cover, thesecond stent cover is distal of the third stent cover, etc. In theembodiments of FIGS. 9-13, the covers are arranged radially about thestent body, i.e., oriented circumferentially upon a longitudinal segmentof the stent body, wherein each of the covers extend partially about thecircumference of the stent body to cover less than a full circumference,and is overlapped by an adjacent cover extending around the samelongitudinal segment. Thus, the cover is overlapped along a given length(longitudinal region) of the stent body. Stated another way, the coverscan overlap longitudinally, in the manner of a fanfold or unrolled map.In each of the embodiments of FIGS. 6-16, the extent of coverage of thestent body changes as the stent bends, as well as depends on the amountof stent expansion allowed by a particular luminal diameter of thevessel (or other body region) the stent is disposed within. The freemovement of the covers increases the flexibility of the stent. As inFIGS. 3C and 3F discussed above, when the stent bends, the coverage mayrelatively shorten along the outer curve as the outer curve length ofthe stent body increases and the coverage may relatively lengthen(increases) along the inner curve as the inner curve length of the stentbody decreases.

Turning first to FIGS. 6 and 6A, the covered stent has a cover/cape 130and a cover/cape 330. Cover 130 is attached at a distal end atattachment region 100 leaving a free end 160. A proximal portion of thecover 130, which includes the free end 160, overlaps a distal portion ofcover 330. Cover 330 is attached at a distal region at attachment region390 leaving free end 360 at a proximal portion. In the illustratedembodiment, cover 130 overlaps/overlies attachment region 390 of cover330. Stated another way, the attachment region 390 and the distalmostedge at distal region 300 is overlapped by outer cover 130. The lengthsof the stent covers 130, 330 are designated by references numerals 10,30, respectively, to show the overlap. Note the length of the overlapregion, in this and the other embodiments disclosed herein, can varyfrom that illustrated. It may also vary in the same stent depending onthe configuration and/or bending of the stent. As can be appreciated,the free end 360 of cover 330 which is not attached to the stent body isunrestricted as it is exposed, i.e., not overlapped, by cover 130.

FIGS. 7, 7A and 7B show how three caped elements can be coupled. Inparticular, the covered stent has a distal cover/cape 130, anintermediate cover/cape 330 and a proximal cover/cape 530. Cover 130 isattached at a distal end at attachment region 100 (adjacent the distaledge) leaving a free exposed/uncovered end 160. A proximal portion ofthe cover 130, which includes the free end 160, overlaps a distalportion of cover 330. Cover 330 is attached at a distal region 300 atattachment region 390 (adjacent the distal edge) leaving free end 360exposed (uncovered). A proximal portion of the cover 330, which includesthe free end 360, overlaps a distal portion of cover 530. Cover 530 isattached at a distal region 500 at attachment region 590 (adjacent thedistal edge) leaving free end 560 exposed (uncovered). In theillustrated embodiment, cover 130 overlaps/overlies attachment region390 and cover 330 overlaps/overlies attachment region 590. The lengthsof the stent covers 130, 330 and 530 are designated by referencesnumerals 11, 31 and 51, respectively, to show the overlap. Note thelengths of the overlap region, in this and the other embodimentsdisclosed herein, can vary from that illustrated. As can be appreciated,the free ends 160, 360 and 560 are unrestricted as they are exposed,i.e., not overlapped by the adjacent cover. The attachment regions 100,300 and 500 are attached to the stent body and can be attached along asmall longitudinal segment as designated by attachment regions/segments100, 390, 590 (and at the distal region of cover 130 (not shown). Theoverlapping covers, which are arranged in a shingle-like arrangement,can be appreciated in the longitudinal cross-sectional view of FIG. 7Bwhich shows proximal region 103 of cover 130 overlapping distal region,including distal attachment region 300, of cover 330 and proximal region303 of cover 330 overlapping distal region, including distal attachmentregion 500, of cover 530. Proximal regions/free ends 303 and 503 ofrespected covers 330, 530 are not covered by a cover. The covers 130,330 and 530 are attached to outer wall 231 of stent body 230. Inalternate embodiments, one or more of the covers can be attached to theinner wall 232 of stent body 230.

FIG. 8 illustrates stent 230 positioned within the covers of FIG. 7. Thecovers 130, 330 and 530 can be attached to stent 230 at a singlecircumferential point attachment such as attachment point 295 for cover130. That is, they are preferably attached at only one end which can bealong a single circumferential ring or alternatively can be attachedalong a short length (longitudinal segment) of a distal region such asregions 390 and 590. Such single circumferential or longitudinalattachment point, combined with said overlapping circumferentialshingles allows the stent to bend without kinking. Note the attachmentpoint could alternatively encompass a full circumference, a partialcircumference, a partial length, and/or combinations thereof, providedthere is a sufficient free end region. Element 100 of first cover 130fixes cover 130 to the stent body at stent attachment element or region295, located on stent 230 between first end 200 and second end 260.Elements 390 and 590 are likewise attached to stent attachment elements,either at a ring-like attachment region such as attachment region 295for cover 130 or along a longitudinal segment. Note the covers in FIG. 8together cover less than a full length of the stent body 230, leavinguncovered distal and proximal regions. Other lengths are alsocontemplated.

The overlapping shingle arrangement can be used with balloon expandable(or mechanical expandable) and self-expanding stents. When aself-expanding covered stent is partially pushed out of the deliverydevice, e.g., catheter, and expands fully, it can pin the cover againstthe vessel wall. However, due to the shingled arrangement of the presentinvention, although a portion of the cover is exposed, and can be pinnedagainst a vessel wall when that segment of the stent body fully expands,remaining portions or remaining covers can be maintained inside thecatheter, which would then not be pinned yet against the vessel wall. Inother words, the stent is not constrained as each cover (cape) can moveindependently so that pinning of one cover does not affect movement ofthe other covers. As the stent is unsheathed, the stent fully expandsdistally and the portion of the stent out of the catheter butimmediately adjacent to it will still be somewhat constrained incircumference by the catheter's constraint of the immediately adjacentsegment of the stent body. Each cover may be temporarily completely freeof pinning/constraint from the catheter as well as the vessel wall as itcomes out of the catheter, either by pushing the stent forward,withdrawing the catheter, or both pushing and withdrawing. Thus, thecovers can be deployed in sequence as desired. Partial delivery of thecovered stent to achieve this advantage is shown in FIG. 13. Forexample, when fully deployed from the delivery member (tube) 900, thefirst cape (cover) 130 can cover partially or fully a lesion prior tofull deployment of the second cape (cover) 330. The first cape 130 asshown outside the delivery member 900 but not yet fully pinned betweenthe stent frame and the vessel wall as a more proximal section (portion)of the stent remains constrained within the delivery member 900. Thefree end region of the cape 130 is still spaced from the vessel wall.The more distal section (portion) of the stent is shown deployed fromthe delivery member 900 so it expands into contact with the vessel wall.A distal portion of the second cover is exposed from the deliverymember; a more proximal section remains inside the delivery member. Ascan be appreciated from the discussion herein, the free end does notrestrict the stent bending. Also note that due to the series of shingledcovers rather than a single cover, and due to the free end, when thestent is partially deployed if the distal cover becomes pinned to thevessel wall by the stent, the stent can still retain its flexibility asthe other portions are deployed since the more proximal covers, with theunattached ends, will not restrict bending of the stent.

The stent covers can overlap in various arrangements. One example of analternate arrangement is shown in FIGS. 7C-7D. In this embodiment,distal and proximal stent covers 180 and 182 overlap intermediate stentcover 184, with a proximal region 180 b of stent cover 180 overlapping adistal region, including distal end 184 a, of stent cover 184 and acover 182 overlapping a proximal region, including proximal end 184 b,of cover 184. The stent cover 180 is attached adjacent distal end 180 aand the opposite end 180 b is unattached forming a free end at aproximal region. Stent cover 182 is attached adjacent distal end 182 aleaving proximal end 182 b unattached forming a free end. A portion ofstent cover 184 is exposed. The stent cover 184 can be attached to thestent covers 180, 182, and/or attached to the stent body 230. Notealternatively, the cover 180 could be attached adjacent the proximal end180 b and/or the cover 182 could be attached adjacent the distal end 182a leaving the opposing ends free floating. The ends of stent cover 184can be affixed to stent body 230 or alternatively one end can beattached and the other free floating. Covers are shown attached to outerwall 231 of stent body 230 but alternatively one or more of the coverscould be inside the stent body 230 attached to the inner wall 232.

The covers as shown in FIGS. 6 and 8 extend around the fullcircumference, i.e., 360 degrees, of the stent body 230. In alternateembodiments, the stent covers extend externally around less than 360degrees. This could include for example 270 degrees, 180 degrees andother amounts/degrees about the stent body 230. FIG. 7E provides oneexample wherein the covers extend about 180 degrees around the stentbody. The covers are configured as half cylinders and are arranged in ashingle like fashion as in the covers of FIG. 7A such that cover 413overlies cover 433 and cover 433 overlies cover 453 (overlapping in aproximal to distal direction). More specifically, cover 413 has a distalend 413 a attached to stent body 230 at attachment region 402 and aproximal unattached free end 413 b, cover 433 has a distal end 433 aattached to stent body 230 at attachment region 404 and a proximalunattached free end 433 b; cover 453 has a distal end 453 a attached tostent body 230 at attachment region 406 and a proximal unattached freeend 453 b. The proximal region of cover 413 overlies the distal region,including the distal end 433 a, of cover 433 and the proximal region ofcover 433 overlies the distal region, including distal end 453 a ofcover 453. In this manner, the shingle-like arrangement leaves the freeends of each cover 413, 433 and 453 exposed for free floating movement.Note the covers alternatively in this and other embodiments disclosedherein can be overlapped in a distal to proximal direction withattachment regions at the proximal ends.

The covers 413, 433 and 453 together cover the majority of the stentbody 230, and extend from its proximal end to its distal end, althoughin alternate embodiments they can extend over a shorter length of thestent body. One or more of the covers can also alternatively bepositioned within the stent body 230, attached to the inner wall insteadof the outer wall, together extending for various lengths within thestent body 230. The covers can alternatively be attached at theirproximal ends instead of their distal ends, leaving free floatingunattached distal ends. Further note in this embodiment, as well as inother embodiments disclosed herein, the covers of the caped stent areshown of substantially the same length, however, alternatively thesecovers as well as the covers of the other caped stents disclosed hereincan be of different individual lengths.

As noted above, the covers can be of various geometric shapes such ascylindrical or semi-cylindrical as illustrated in FIGS. 6-8. FIGS. 7Fand 7G show the covers as triangular shaped to provide an illustratedexample of a different shaped cover. FIG. 7F shows caped stent 700having four substantially triangular covers 720, 722, 724 and 726arranged in an overlapping shingle-like arrangement (like scales on afish). Covers 720, 722, 724, 726 are attached at respective distal ends720 a, 722 a, 724 a and 726 a leaving unattached free floating proximalends. The proximal region of cover 720 overlies the distal region,including the distal end 722 a, of cover 722, the proximal region ofcover 722 overlies the distal region, including the distal end 724 a, ofcover 724 and the proximal region of cover 724 overlies the distalregion, including the distal end 726 a, of cover 726. Covers 720, 722,724, 726 extend over less than 360 degrees of the stent body 230terminating at respective edges 720 b, 722 b, 724 b, 726 b. It should beappreciated that a different number of covers could be provided. Thecovers can extend about the circumference of the stent body 230different degrees (amounts) than that shown. That is, the covers in thisand in the other embodiments could together cover a different amount ofthe stent body circumferentially and/or axially than the extent ofcoverage illustrated in the drawings.

Covered stent 750 of FIG. 7G illustrates an example wherein thetriangular shaped covers together cover less than a majority of a lengthof the stent body 230, leaving longitudinal (axial segment region 233)exposed (uncovered) and covering less than the full 360 degrees of thestent body (leaving region 235 of stent body 230 exposed). Covers 752,754, 756 are arranged in overlapping shingle-like arrangement. Covers752, 754 and 756 are attached at respective distal ends 752 a, 754 a,756 a leaving unattached free floating proximal ends. Thus, the proximalregion of cover 752 overlies the distal region, including distal end 754a, of cover 754 and the proximal region of cover 754 overlies the distalregion, including distal end 756 a, of cover 756.

The overlapping coverings to create an impermeable shingling effect asdescribed herein enables each cover to be deployed completely, ifdesired, without fully deploying other covers. The advantage, forexample, is that a fistula may be covered without fully deploying theentire covered stent. Another advantage of this feature is that itameliorates the need for different-sized covered stents. Furthermore,the coverings can collectively cover longer lengths and/or diameters ofa stent without significantly impeding the flexibility of the stent.

FIGS. 6-7G show the stent covers extending along longitudinal (axial)segments of the stent body, overlapping in a shingle-like arrangement.In the embodiments of FIGS. 9-12, the covers overlap in a shingle-likearrangement circumferentially about the same longitudinal segment of thestent body. In FIGS. 9 and 10, the covers are shown in the rolled(undeployed) condition; in FIGS. 10A and 10B the covers are shown in theunrolled (deployed condition). Note in the “rolled condition” as definedherein, the covers are collapsed, i.e., are “wrinkled” or “bunched” sothat they form an irregular non-even configuration. When deployed, thecovers “unravel” to form a more regular and even cover about the stentbody.

In FIGS. 9-10B, instead of having a single continuous cover there aremultiple circumferentially “shingled” covers in the form of sheets offabric, preferably substantially or entire impermeable, wherein thenonattached or free segment of sealing fabric from one sheet overlapsalong an axial region with the attached segment of the adjacent sheet.This shingling allows the stent to more freely bend in zones where thereis no attachment. The covers can be on the inner surface and/or outersurface of the stent body (frame) 230. Thus, the cover has multipleintermittent circumferential attachment points to the stent body 230,and has excess length of fabric at its free end compared to the“frame/skeleton” in each segment between the attachments, to allow theskeleton to bend freely without being restricted by the fabric. Theextra fabric will allow relative lengthening of the skeleton on theouter side of the bends of the stent within the vasculature. In someembodiments, the frame can be an open ended roll as well, which canallow some stents to conform to a greater variety of vessel diameters.That is, the stent frame may have a rolled configuration where thecylinder is not closed longitudinally.

More specifically, a plurality of covers 930 are attached to stent body230 at linear connection points 935 on the outer surface of stent 230.The connection can be at the edges of each cover 930 at attachment 935or alternatively can extend linearly from the edge along a longitudinalaxis of the stent body 230, e.g., extending from the distal edge 933 tothe proximal edge 936 of the cover 930. The stent covers 930 arepositioned in a medial region of the stent body 230, between the ends200 and 260. By extending less than the length of the stent body, aproximal region and a distal region of the stent body 230 are uncovered,although shorter or longer covered regions are also contemplated.

In the delivery (undeployed) position, each cover 930 is in a collapsedundeployed condition and the covers 930 extend around the circumferencesof the stent body as shown in FIGS. 9 and 10 and are positioned in amedial region of the stent body 230. In some embodiments, the covers 930are maintained in the undeployed condition within a delivery sheath (notshown) which constrains the covers 930 in the undeployed configuration.As shown in FIGS. 9 and 10, the covers in this collapsed position areirregular/wrinkled. The covers can extend over a minority or majoritycircumferential portion of the stent body, and in some embodiments canextend over 100% of the circumference (such as shown in FIG. 10). Forexample, they can extend over 360 degrees and over 125% of thecircumference. Their degree of overlap will decrease when the stent isdeployed and the covers likewise move to the deployed configuration (seeFIG. 10A). By way of example, three covers can be provided eachextending around ½ (180 degrees) of the stent body in the collapsedconfiguration and extending around ⅙ of the stent body when in theexpanded deployed configuration. With the stent crimped, the coverswould overlap more than when the stent is expanded and each cover couldin some embodiments go all the way around the entire stent and even insome embodiments in the crimped position extend more than once aroundthe stent body. FIG. 10C shows an alternate embodiment wherein the threestent covers in the collapsed configuration extend a shorter distancearound the circumference compared to the embodiment of FIG. 10. FIG. 11Ashows an embodiment having more than three covers around the stent body230.

It should be appreciated, that a different number of covers, covers ofdifferent lengths, and covers extending around different amounts(degrees) of the stent body in the deployed and undeployedconfigurations of the stent are contemplated.

When deployed, the covers unroll (uncoil, unwrap) into the overlappingcondition shown in FIGS. 10A and 11A. (The covers can unwrap as thestent expands). When deployed, cover 930 a of the covers (collectivelyreferred to by reference numeral 930) has an end region 960 with edge932 forming a free end which overlaps an axial region of cover 930 b,cover 930 b has an end region or edge 938 which overlaps an axial regionof the adjacent cover, etc. In this manner, each cover has a free axialregion 960 from end 933 to end 936 which overlaps an axial region fromend 933 to end 936 of an adjacent underlying cover. The line ofattachment of the cover to the stent body 230, extending from first end933 to second end 936, is represented by the dashed line in FIGS. 10Aand 11A. Thus, each cover has an uncovered free end (region) 960extending along a longitudinal (axial) length, i.e., extending along alongitudinal segment of the stent body 230. In this way, the pluralityof unrolled seal elements (covers) 930 overlap such that each free end960 makes a flap over the end at the adjacent linear connection pointsto form a fanfold-type overlap covered stent, thereby forming a coverageband of overlapping free ends 960 about the circumference of stent 230.Note the number of covers encircling the stent body 230 can varydepending on the dimensions of the cover and the desired amount ofcoverage. The length of the covers can also vary. As can be appreciatedin FIGS. 10A and 11A, in the deployed position, the covers form asmoother more even outer surface as compared to the wrinkled irregularouter surface when collapsed.

FIG. 11B illustrates an alternate embodiment of the covered stent of thepresent invention. FIG. 11A shows an alternate embodiment having eightcovers 930 as an example of a covered stent with multiple covers. Asdescribed above, three covers 930 a, 930 b, and 930 c are each attachedto a stent body 230 along a longitudinal segment 932 extending from edge932 (or adjacent edge 932) to edge 936) or adjacent edge 936. Thecovered stent of FIG. 11B is identical to the covered stent of FIG. 11Aexcept the covers 940 have an additional attachment. That is, the covers940 differ from covers 930 by having an attachment region 945 at adistal end (or alternatively at a proximal end) which extend radiallyabout the circumference of the stent body. In all other respects, covers940 a, 940 b, 940 c, etc. (collectively referred to as covers 940) areidentical to covers 930 and overlap in the same manner as covers 930 asthe axial overlapping regions extend from end 942 to end 936 (oradjacent these ends).

The covered stents of FIGS. 9-11B have covers which together extendaround the entire circumference of the stent body 230 (the entire 360degrees). In alternate embodiments, such covers can extend for less than360 degrees such as for example 270 degrees, 180 degrees and otheramounts/degrees about the stent body 230. FIG. 11C provides one examplewherein the covers collectively extend about 180 degrees around thestent body, the coverage terminating along edge 956. The covers 950 arearranged in a shingle like fashion like the covers of FIG. 11A such thatcover 950 a overlaps cover 950 b and cover 950 a is overlapped by cover950C. In this manner, a circumferential region 238 of stent cover 230 isexposed. Covers 950 are attached along an axial region or edge as shownin dashed lines 954.

It should be appreciated that in the circumferential overlap of theembodiments of FIGS. 9-1 IC, the covers can be placed at a medialportion of the stent or at a more distal region or at a more proximalregion. They can also cover a majority or less than a majority of theaxial length of the stent body as well as cover the entire or less thanthe entire circumference of the stent body. “Majority” as used hereindenotes a range from more than 50% to 100%.

In the embodiment of FIG. 11D, the covered stent has circumferentialoverlapping covers 970 a, 970 b, 970 c, etc. (collectively referred toas covers 970), overlapping in the same fashion as covers 930 a, 930 band 930 c of FIG. 11A. The covers 970 can have a coiled (wrapped) andunrolled uncoiled (unwrapped) configuration like covers 930. However,this embodiment differs from the embodiment of FIG. 11A in that anadditional cover 980 is provided. Covers 970 overlap a distal regionincluding distal edge 984 of cover 980. Cover 980 is attached about itscircumference to stent body at distal region 985. Proximal end region986 is unattached and forms a free end. Thus, in this embodiment, thecovers 970 have free ends (e.g., ends 972, 975, etc.) extending along alongitudinal segment of the stent body 230 and cover 980 has a free end986 extending circumferentially about the stent body. The free ends ofthe covers are exposed. Covers 970, 980 can cover the entire length ofthe stent body 230 or a portion, as in FIG. 11D, leaving distal andproximal regions of the stent body 230 exposed.

In some embodiments of the present invention a second stent can beprovided which pins the cover between the exterior of the covered stentbody and the interior of the second stent. This is shown for example inthe embodiment of FIGS. 14-16. Covered stent 800 has cover 810 attachedto the stent body 804 at a distal end at attachment region 811 (adjacentthe distal edge 810 a) leaving an unattached free end 810 b. A proximalportion of the cover 810, which includes the unattached free end 810 b,overlaps a distal portion of cover 812. Cover 812 is attached to stentbody 804 at a distal region at attachment region 813 (adjacent thedistal edge 812 a) leaving a free end unattached end 812 b. A proximalportion of the cover 812, which includes the free end, overlaps a distalportion of cover 814. Cover 814 is attached to the stent body 804 at adistal region at attachment region 815 (adjacent the distal edge 814 a)leaving a free unattached end 814 b. In the illustrated embodiment,cover 810 overlaps/overlies attachment region 813 and cover 812overlaps/overlies attachment region 815. The stent body 804 forms aninner stent or inner frame. An outer stent 802 is placed over the covers810, 812, 814 so that the covers are sandwiched between the inner stent804 and outer stent 802. Note the lengths of the overlap region, in thisand the other embodiments disclosed herein, can vary from thatillustrated. Also, in some embodiments, the outer stent is positionedonly over some of the covers or extends for a length less than the totalaxial length of the adjacent covers. The overlapping covers 810, 812,814 are arranged in a shingle-like arrangement as can be appreciated inthe cross-sectional view of FIG. 16 which shows the proximal region ofcover 810 overlapping distal region, including distal attachment region813, of cover 812 and the proximal region of cover 816 overlapping thedistal region, including distal attachment region 815, of cover 814.Gaps 816 and 816 a are shown between the outer surface of inner stent804 and the inner surface of outer stent 802.

As can be appreciated, in the embodiments of FIGS. 14-16 the cover,e.g., the “fabric” is pinned between the two layers of stents. Thesecond outer stent can either be a second built-in layer with the cover,e.g., fabric layer, sandwiched in between (but the fabric mostlyunattached), or placed separately as a separate, non-attached layer.This second stent (skeleton) can often minimize the risk of endoleaks atthe non-attached regions. Endoleaks can be minimized where the fabriclayer is not fully attached—if a second stent does not pin the fabric tothe first stent then some of the fabric layers may have some freedom ofmovement—especially in regions where they are covering an aneurysm or afistulous hole and not pinned fully to a vessel wall. When they havesome freedom of motion after implanted, blood flow can potentiallysometimes flap them open, especially in the “shingled” version. In thistwo-layer configuration, with an inner stent that has outer cover(s),the outer stent can in some embodiments have no covers at all, butrather have a frame alone that will act similarly to a vessel wall topin the cover(s) between the inner stent and the frame of the outerstent. In this case, a stent is over a vessel segment entailing alesion, such as an aneurysm or a fistulous hole in the vessel, and isover the stent body of the inner stent. Alternatively, in this two layerconfiguration, with an outer stent that has inner cover(s), the innerstent can in some embodiments have no covers at all, but rather have aframe alone that will act similarly to a vessel wall to pin a coverbetween the inner stent and the stent body (frame) of the outer stent.Alternatively, one or both of the outer and the inner stents can haveouter covers. In some embodiments, one or more covers are attached to anouter wall of the inner layer and/or are attached to an inner wall ofthe inner layer and/or are attached to an outer wall of the outer layerand/or are attached to an inner wall of the outer layer.

If a portion of the stent cover is not well apposed to a vessel wall, ascan occur when it is overlapping a large fistula, a second similarcovered stent can be placed inside the first covered stent, and theframe of the first covered stent will help secure the cover(s) of thesecond covered stent. Similarly, a different covered or uncovered stentcan be used as the initial outer stent, provided such outer stent hassmall enough interstices that the cover(s) of the second inner stentcannot herniate through those interstices. Thus, is some embodiments, anadditional stent with outer covers or no covers may be subsequentlypositioned inside another stent to help secure the covers and avoidvascular obstruction. An example is illustrated in FIGS. 19A and 19B. InFIG. 19A, the covered stent is shown positioned next to an opening in avessel. This can be a fistula, an aneurysm, or other structure. Incertain applications, the free end of one of the covers, e.g., themiddle cover 330, can protrude a bit into the opening, thus enablingleakage of blood under the cover 330. Such endoleak is prevented asshown in FIG. 19B by use of an outer stent 331. The outer stent 331 ispositioned in the vessel, across the opening, and then the covered stentof the present invention is inserted within the outer stent. The coveredstent can be that as described herein, and could have the cover on theinner wall and/or the outer wall. In the embodiment of FIG. 19B, themulti-layered stent could have an outer woven or braided stent and innerstent with larger openings formed by laser cut, a series of struts, etc.In some embodiments the porosity of the inner stent exceeds the porosityof the outer stent and the porosity could be between about 70% and about99.9%, and more preferably greater than about 80% porosity, although agreater or smaller porosity is also contemplated. The porosity of theouter stent could be between 0% and about 80%, and more preferably be75% or less, although a greater or smaller porosity is alsocontemplated.

The covered stents of the present invention could optionally include anadditional structure to minimize endoleaks such as adhered hydrogel. Thehydrogel can be in the form of a coating adhered to the stent, e.g., thestent body/frame (outer and/or inner stent body in embodiments with twostent layers) and/or the cover and/or to one or more of the covers ifmultiple covers are provided. An example of the hydrogel preventingendoleaks is if the cover has a fold when placed, and blood might beable to get through, the hydrogel could swell and fill the gap.

FIGS. 17 and 18 illustrate alternate embodiments of the multi-layeredcovered stent. In FIG. 17, the outer stent 850 is composed of a metallicmaterial. It can be formed from a laser cut tube or by other methods andcan be expandable via self-expansion or balloon or mechanical expansion.The outer stent can also be formed of other materials, includingpolymeric material. The inner stent 852 is formed of a woven material,e.g., a braid, and has less porosity than the outer stent. The porosityof the outer stent could in some embodiments by way of example bebetween about 70% to about 99.9% and more particularly could be 80% ormore. The inner stent could have a porosity less than 75% in someembodiments. The inner stent can also be formed of other materials. Theone or more covers 854 are interposed between the two stents 850 and852. In the alternate embodiment of FIG. 18, the outer stent 860 isformed from the woven material, e.g., a braid, and the inner stent is ametallic material formed from a laser cut tube or other methods. Theinner stent can be formed of self expandable materials or formed ofballoon expandable or mechanically expandable materials, includingmetallic or polymeric materials. The one or more covers 864 areinterposed between the two stents 860, 862. In either of theseembodiments, one or more of the covers can be attached to the outer wallof the outer stent, the inner wall of the outer stent, the outer wall ofthe inner stent and/or the inner wall of the inner stent, orcombinations thereof.

FIGS. 20A-20C illustrate alternate embodiments of the multi-layeredstent without the covers. In these embodiments, the outer stent isformed of a woven material and the inner stent is more open, i.e., has agreater porosity, and formed of a self-expanding or balloon (ormechanical) expandable material including metallic or polymericmaterials, to facilitate expansion of the outer stent. In FIG. 20A,outer stent 870 is the same length as inner stent 872. In the embodimentof FIGS. 20B and 20C, the outer stent 885 has a longer length andextends beyond both the proximal and distal ends of inner stent 887. Inthe embodiment of FIGS. 20D and 20E, the outer stent 888 has a longerlength and extends beyond only one end (the proximal or distal end) ofinner stent 889. In alternate embodiments, the inner stent can have alonger length than the outer stent such that it extends beyond one orboth ends of the outer stent. In these embodiments, the woven layer,being the outermost layer abuts the vessel wall. The inner layer helpsthe stent expand more easily as it moves from a collapsed condition toan expanded condition as braided stents are “lazy” and sometimesreluctant to expand once crimped. Also, more porous stents are generallymore efficient at expanding than lower porosity stents, such as lowporosity woven stents.

In the embodiments of FIGS. 17A-20C, the less porous layer is flowdiverting and has less pores to touch the endothelium so there is lesslikelihood of endoleaks, e.g., endoleak into the aneurysm. For example,by changing the flow dynamics by reducing the porosity, it causes theaneurysm to shrink over time.

In some embodiments, the more porous stent can have a porosity of over50% and preferably over 80%. The less porous stent can have a porositybetween 0% to about 80%, and in some embodiments between about 40% and75%, depending on the porosity of the more porous stent, i.e., the %porosity of less porous stent is less than the % porosity of the moreporous stent. Other porosity percentages are also contemplated.

The covered stents of the present invention are preferably delivered anddeployed using a catheter or sheath (not shown). The covered stents canbe deployed either out a distal end hole or a side hole formed in themicrocatheter or sheath. The covered stents of the present invention canbe either self-expanding so they expand when exposed from the deliverydevice or mechanically expanded such as expanded by a pull wire or anexpandable structure within the stent or expanded by inflation of aballoon positioned within the stent and mounted on the catheter, and/orcombinations thereof.

In the covered stents of the present invention, as discussed above, thecovers (capes) cape could be attached to the stent body either at oradjacent the distal end of the stent body or at or adjacent the proximalend of the stent body, or at other regions, including for example medialregions, along the stent body. When the stent is deployed/expanded usinga balloon then in preferred embodiments the cover is attached toward theproximal end of the stent body because the balloon pushes expands/opensthe stent. When stent is deployed using a wire (not shown), then inpreferred embodiments the cover is attached toward the distal end of thestent body because the wire is pulled in a proximal direction.Nonetheless, alternate configurations are envisioned with each type ofexpansion.

As discussed above, the shingling effect can be achieved with covers ofvarious geometric shapes that are not necessarily circumferential aroundthe entire stent. Non-limiting examples include multiple triangles,wherein the covered segment has shingling that will effectively entirelycover the “covered” zone. Again, the shingled coverings can be disposedupon the inner surface or outer surface or both the inner surface andouter surface of the stent body.

As discussed above, the covers of the present invention can be on theoutside or inside of the stent body, attached to an outer wall/outerstructure or an inner wall/inner structure of the stent body. In someembodiments, one or more of the covers can be attached on the outsidewhile one or more of the other covers can be attached on the inside. Insome embodiments, the attachment is on the distal end (spanning apunctate/very short distance) of the covered zone. The covering cancover anywhere from about 0.1% to 100% of the stent body. In someembodiments, it covers the central or medial portion of the stent body(skeleton) while leaving the distal and proximal regions uncovered; inother embodiments it covers the distal region leaving the proximalregion uncovered and in other embodiments it covers the proximal regionleaving the distal region uncovered. In some embodiments, the attachmentzone is circumferentially around the stent in a distal region which canmake delivery easier. However, it can alternatively be at a proximalregion as well as discussed above. If attached at a medial region, itcan be attached so there are two unattached free ends at each end of thestent.

The covered stents of the present invention with free unattached endsresults in covered stents which can more freely bend along the contourof tortuous vessels, without kinking or straightening the vessel,compared to prior stents that have multiple or diffuse attachmentsbetween the cover and the stent body (skeleton). This also increases thetortuosity of the anatomy of vessels within which these covered stentscan be safely and effectively delivered and deployed. The outer end ofany curve requires a larger radius than the inner curve and the diffuseattachments of a typical covered stent require a fixed amount of thecover, e.g., fabric, per interstices or zone of the stent, thus makingthe stent much stiffer.

The covers of the present invention could be in the form of a “fabric”such as nylon, Dacron, pericardium, polyester, PET, PTFE or any othernonporous or minimally porous material, wherein the fabric is onlyattached on one side, such as the distal end of the fabric or theproximal end of the fabric, to the stent body. The attachment zone canbe from as small as a punctate point circumferentially around the stent,to as much as 98%, provided there is a sufficient free end region toreduce stiffness as discussed above. In preferred embodiments, theattachment point would be very short. In preferred embodiments, the“fabric” layer is outside the “frame/skeleton” layer, howeveralternatively it could be inside. When attached on the outside (exteriorsurface of the stent body), it will contact the vessel walls upondeployment and full stent expansion to the circumference of the vessel;when, attached on the interior surface such that it is disposed withinthe stent skeleton, the skeletal outer surface will abut the vesselwall.

The skeleton is a separate component to which the one or more covers areattached. Preferably, the cover is composed of a different material thanthe stent body. The “skeletons” of the present invention can be composedof semi-rigid but flexible materials, such as metal alloys (containingchromium cobalt, and/or platinum, and/or nickel, titanium, steel, etc.)or synthetic fibers such as vicryl. The covers are preferably attachedto the stent body in manufacture so the covered stents are inserted intothe body and placed in position with the covers attached to the stentbody.

The stent covers can expand independently of each other and/orindependently of the stent body except at the attachment site.

Each of the embodiments disclosed herein can optionally have at leastone uncovered opening in the covered stent.

Each of the embodiments disclosed herein can optionally have multiplecovered zones and can optionally have multiple uncovered zones.

Elements of the covered stents of the present invention may bebiodegradable or nondegradable. Alternatively, elements may be composedof both biodegradable and nondegradable elements. An element can becomplete components of a particular part of the covered stents of thepresent invention or sub-components of each part.

The covered stents may optionally contain radiopaque components and/orradiopaque markers. These can be especially beneficial at ends of thestent and at the ends of the covered zone. Radio-opaque materials andmarkers can also be provided in other regions of the covered stent, andin some embodiments can be provided throughout the covered stent.

In some embodiments, the overlapping and/or shingled covers, (e.g.,fabric layers) may have an additional “frame/skeleton” latticesupporting it, wherein that skeleton/frame is primarily supporting that“fabric” layer, and is an independent (but attached) skeleton layer tothe main skeleton cylinder of the stent. For example, if there aretriangular shingles of fabric attached on one end of the triangles tothe outside of a main metal skeleton/cylinder, each triangle of fabricmay optionally have additional metal struts supporting it, wherein suchskeleton is primarily free from the main cylinder (e.g., no more than70% of the support skeleton for the unattached portion of the fabric isattached to the main skeleton cylinder).

In some embodiments, the stent skeleton is semi-cylindrical, having adiscontinuous diameter and longitudinal edges overlapping in a loosecoil in an undeployed state. The stent unrolls into an overlapping butsubstantially cylindrical or semi-cylindrical shape as the skeletonexpands when inserted in a target vessel. In such stent configurations,the capes (covers) can be attached longitudinally.

The covered stents of the present invention may have branched stentelements. The stents can be fully re-sheathable or partly re-sheathable.The stent elements of the present invention may optionally bedetachable.

It should be noted that in one representative example of a skeleton(stent body) and cover/fabric layer, which are attached in themanufacturing process, the fabric layer has an attachment length(relative to fabric) that can be as small as 0.00001% and as much as98%, provided a sufficient free end is formed. In these embodiments, thefabric is attached at a location such that it covers a percentage of theskeletal surface. Relatively small attachment zones are present inpreferred embodiments.

The degree of overlap of the stent covers can vary depending upon thediameter of the expanded stent skeleton and the lumen within which it isdeployed.

It will be understood by those skilled in the art that the aboveparticular embodiments are shown and described by way of illustrationonly. The principles and the features of the present disclosure may beemployed in various and numerous embodiments thereof without departingfrom the scope and spirit of the disclosure as claimed. Theabove-described embodiments illustrate the scope of the disclosure butdo not restrict the scope of the disclosure.

Although the invention has been described in detail in the foregoingembodiments for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose, and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention.

Although the apparatus and methods of the subject invention have beendescribed with respect to preferred embodiments, which constitutenon-limiting examples, those skilled in the art will readily appreciatethat changes and modifications may be made thereto without departingfrom the spirit and scope of the present invention as defined by theappended claims.

Additionally, persons skilled in the art will understand that theelements and features shown or described in connection with oneembodiment may be combined with those of another embodiment withoutdeparting from the scope of the present invention and will appreciatefurther features and advantages of the presently disclosed subjectmatter based on the description provided.

Throughout the present invention, terms such as “approximately,”“about”, “generally,” “substantially,” and the like should be understoodto allow for variations in any numerical range or concept with whichthey are associated. It is intended that the use of terms such as“approximately”, “about”, “substantially”, and “generally” should beunderstood to encompass variations on the order of 25%, or to allow formanufacturing tolerances and/or deviations in design.

The recitation of numerical ranges by endpoints includes all numberswithin the range. Although terms such as “first,” “second,” “third,”etc., may be used herein to describe various operations, elements,components, regions, and/or sections, these operations, elements,components, regions, and/or sections should not be limited by the use ofthese terms in that these terms are used to distinguish one operation,element, component, region, or section from another. Thus, unlessexpressly stated otherwise, a first operation, element, component,region, or section could be termed a second operation, element,component, region, or section without departing from the scope of thepresent invention.

Each and every claim is incorporated as further disclosure into thespecification and represents embodiments of the present disclosure.Also, the phrases “at least one of A, B, and C” and “A and/or B and/orC” should each be interpreted to include only A, only B, only C, or anycombination of A, B, and C.

What is claimed is:
 1. An intravascular stent comprising: a) a stentbody having a longitudinal axis, a first portion, a second portion and aplurality of openings; b) a first cover overlying the stent body tocover the first portion of the stent body and extending longitudinallyover the first portion, the first cover having a first region and anunattached region, the unattached region having a free end, the firstcover attached to the stent body at the first region; c) a second coveroverlying the stent body to cover the second portion of the stent bodyand extending longitudinally over the second portion, the second coverhaving a first region and an unattached region, the unattached regionhaving a free end; d) wherein the first cover overlaps the first regionof the second cover and a portion of the unattached region of the secondcover is not overlapped by the first cover.
 2. The intravascular stentaccording to claim 1, wherein the first cover overlaps the second coversuch that less than a majority of the second cover is overlapped by thefirst cover.
 3. The intravascular stent according to claim 1, whereinthe first cover overlaps the second cover such that a majority of thesecond cover is overlapped by the first cover.
 4. The intravascularstent according to claim 1, wherein the free ends of the first andsecond covers are axially spaced.
 5. The intravascular stent accordingto claim 1, wherein the first cover and the second cover are attached toan inner wall of the stent body.
 6. The intravascular stent according toclaim, wherein the first cover and the second cover are attached to anouter wall of the stent body.
 7. The intravascular stent according toclaim 1, wherein the stent is inserted into a body of a patient with thefirst and second stent covers attached to the stent body.
 8. Theintravascular stent of claim 1, wherein the first and second covers areattached to an outer wall of the stent body, and the stent furthercomprises a second stent body positioned over the first and secondcovers.
 9. The intravascular stent according to claim 1, wherein thefirst and second covers extend around a full 360 degrees of the stentbody.
 10. The intravascular stent according to claim 1, wherein thefirst and second covers extend around less than a full 360 degrees ofthe stent body.
 11. The intravascular stent according to claim 1,wherein the first and second covers are each attached to the stent bodyat an attachment site, and the first and second covers are expandableindependent of the stent body except at the attachment site.
 12. Theintravascular stent according to claim 1, further comprising a thirdcover overlying the stent body to cover a third portion of the stentbody and extending longitudinally over the third portion, the thirdcover having a first region, and an unattached region, the second coveroverlapping a portion of the third cover so the first, second and thirdcovers for a shingle-like arrangement.
 13. The intravascular stent ofclaim 1, wherein the at least part of the stent body has a hydrogeladhered thereto.
 14. The intravascular stent of claim 1, wherein the atleast part of the first cover has a hydrogel adhered thereto.
 15. Anintravascular stent comprising: a) a stent body having a longitudinalaxis and a plurality of openings; and b) a first cover overlying thestent body to cover a first segment of the stent body and extendinglongitudinally over the first segment of the stent body, the firstsegment having a first region and a second region; d) wherein uponbending of the stent body, a portion of the first cover moves axiallywith respect to the stent body so a length of the stent body covered bythe first cover is reduced along an outer curve of the stent body. 16.The intravascular stent of claim 15, further comprising a second coveroverlying the stent body to cover a second segment of the stent body,said second segment having a first region and a second region andwherein upon bending of the stent body, a portion of the second covermoves axially with respect to the stent body so a length of the stentbody covered by the second cover is reduced along an outer curve of thestent body.
 17. The intravascular stent of claim 16, wherein uponbending of the stent body, a portion of the second cover lengthensrelative to the stent body along an inner curve of the stent body. 18.The intravascular stent according to claim 16, wherein the first coverand second cover are each attached to the stent body at an attachmentsite, and the first and second covers are expandable independent of theframe except at the attachment site.
 19. The intravascular stentaccording to claim 15, further comprising a third cover overlapping thesecond cover and the second cover is overlapped by the first cover, thefirst, second and third covers forming a shingle like arrangement. 20.The intravascular stent according to claim 15, wherein the first andsecond stent covers are attached to the stent body prior to insertion ofthe stent and placement of the stent within the vessel.
 21. Theintravascular stent of claim 15, wherein the at least part of one orboth of the stent body or first cover has a hydrogel adhered thereto.22. An intravascular stent comprising: a) a stent body having alongitudinal axis, a first portion, a second portion and a plurality ofopenings; and b) a first cover having an attachment end attached to thestent body and an opposing free end which is exposed, the free endmovable with respect to the stent body to reduce a stiffness of thestent body.
 23. The intravascular stent according to claim 22, furthercomprising a second cover having an attachment end attached to the stentbody and an opposing free end which is exposed and movable with respectto the stent body to reduce a stiffness of the stent body, the first andsecond covers arranged in a shingle-like arrangement to cover axialsegments of the stent body, the first and second arranged so that thefree end is not overlapped by an adjacent cover.